Magnetically actuated demand contact device



A ril 18, 1967 E. H. DAY I 7 3,315,192

MAGNETICALLY ACTUATED DEMAND CONTACT DEVICE Filed Oct. 22, 1965 2Sheets-Sheet 1' //VVE/V7'0/? [AMER H. DAV

ATTORNEY E H. DAY 3,315,192

MAGNETICALLY ACTUATED DEMAND CONTACT DEVICE A ril 18, 1967 2Sheets-Sheet 2 Filed Oct. 22, 1965 United States Patent MAGNETICALLYACTUATED DEMAND CONTACT DEVICE Elmer H. Day, 24 Hillcrest Ave.,Erdenheim, Pa. 19118 Filed Oct. 22, 1965, Ser. No. 500,735 6 Claims.(Cl. 335-153) This invention relates to a magnetically actuated demandcontact device, and more particularly to such a device that is suitablefor use in conjunction with 'electric watthour meters for actuatingdemand meters.

Integrated demand recorders are used with watthour meters to produce aseparate record of kilowatt hours used during a certain selected demandinterval. The devices heretofore used to actuate the recordinginstrument, which is usually separate from the watthour meter, have hadundesirable qualities. The cam devices of the prior art greatly increasefrictional torque which reduces the accuracy at light load. Thisfrictional torque was overcome by a compensating winding which requiredcareful adjustment to prevent excessive speed at no load. Frequentadjustment was necessary to accommodate changes in friction as thecontact device aged. Also, the friction was a function of the camposition and varied during the cam cycle.

In developing the invention it was observed that the presence of strongvariable electromagnetic fields within and around where reeds wereemployed caused them to vibrate and make accidental contact.

Other prior demand contact devices, also, were not compact and requiredlarger space than is available or desirable to employ. I

Frequent maintenance and servicing have been necessary with the devicesnow available.

The principal object of the present invention is to provide amagnetically actuated demand contact device that is simple, has smallspace requirements and is exceedingly compact, which is inexpensive toconstruct, but which is sturdy and reliable in service.

A further object of the present invention is to provide a magneticallyactuated demand contact device that is unaffected by the intenseelectrical fields surrounding it.

A further object of the present invention is to provide a magneticallyoperated demand contact device that is easy to install and is readilyadaptable to the different watthour meters in general use.

A further object of the present invention is to provide a magneticallyoperated demand contact device that requires a minimum of maintenanceand adjustments because of the reduction of variable friction.

Other objects and advantageous features of the invention will beapparent from the description and claims. The nature and characteristicfeatures of the invention will be more readily understood from thefollowing description taken in connection with the accompanying drawingsforming part thereof, in which:

FIGURE 1 is a view in perspective of a watthour meter having the demandcontact device of the invention incorporated therewith;

FIG. 2 is a rear elevation of the register of a watthour meter havingthe invention incorporated therewith;

FIG. 3 is a vertical sectional view, taken approximately on the line 33of FIG. 2 and also including parts of the meter of FIG. 1;

FIG. 4 is a fragmentary vertical sectional view, enlarged, takenapproximately on the line 44 of FIG. 3;

FIG. 5 is a horizontal sectional view taken approximately on the line5-5 of FIG. 4;

FIG. 6 is an end elevational view of the structure shown in FIG. 5;

3,315,192 Patented Apr. 18, 1967 ICC FIG. 7 is a schematic view of anelectrical circuit used with a graphic meter demand recorder;

FIG. 8 is a schematic view of the electrical circuit used with amagnetic tape demand recorder; and

FIG. 9 is a fragmentary sectional view of a modified form of magneticshield.

It should, of course, be understood that the description and drawingsherein are illustrative merely, and that various modifications andchanges can be made in the structure disclosed without departing fromthe spirit of the invention.

Like numerals refer to like parts throughout the several views.

Referring now more particularly to the drawings, a watthour meterassembly 10 of wellknown type is shown having the demand contact devicein accordance with the invention mounted thereon. The watthour meterassembly 10 includes a back mounting plate assembly 11 which includes aback plate 12 of non-electrical conductive synthetic plastic material,and which is adapted to carry the conventional metal retaining ring andtransparent glass cover (not shown).

The meter assembly 10 also includes an intermediate mounting plate 13,and in front thereof, a watthour register assembly 14.

The mounting plate assembly 11 includes a plurality of contact plugs(not shown) for connection to a source of electric power, theconsumption and demand of which is to be recorded.

Between the mounting plate 13 and the back mounting plate assembly 11,stator laminations 18 are shown energized by and responsive to thecurrent flow. The mag- :netic field induced in the laminations 18 iseffective for rotating a disc 20. The disc 20 is mounted at the centerthereof on a shaft 17 which is journaled in bearings in the conventionalmanner, the upper bearing 21 therefor being shown as carried by amounting plate extension 24, and held in place by a screw 27.

by mounting pins 31 which are secured to the plate 30 and extend intosockets 37 and are held therein by screws 38.

The register assembly 14 also includes a dial plate 32 parallel to andspaced forwardly from the back plate 30 and carried on rods 39.

The space between the back plate 30 and the intermediate plate 13 isrestricted in most available meters but is sufficient to receive thecompact demand contact assembly 35 of the present invention.

The worm wheel 26 is mounted on a register input shaft 40 which carriesa worm 41. The worm 41 which engages a gear 48 on a main register shaft50 actuates through gearing 49 the respective register indicators 51with respect to their indicia on the dial plate 32.

The drive shaft 40, intermediate its ends, has a cylindrical magnet 52secured thereto for rotation therewith. The magnet 52 preferably has twopoles, one of which is positive (N pole) and the other of which isnegative (S pole), with the magnetic flux from these poles extendingradially from the cylindrical surface. The magnet 52 is made from anydesired material but it is preferred to employ a ceramic permanentmagnet of high magnetic intensity, as it is relatively unaffected bymoisture, by temperature changes, or by eddy currents and is anelectrical non-conductor. A suitable material for this purpose isavailable under the name Ceramagnet from Stackpole Carbon Co., St.Marys, Pa.

A reed switch mechanism 55 is provided adjustably mounted on the plate30 and is adapted to movement towards or away from the shaft 40 at anincreasing or decreasing angle with respect to the shaft 40.

The reed switch mechanism 55 includes a mounting frame plate 56 with anelongated slot 57 through which a mounting screw 58 extends into theback plate 30.

The mounting frame plate 56 has spaced arms 59 between which a block 60of synthetic plastic insulating material is positioned. The block 60positions a reed switch capsule 62 within the arms 59.

The capsule 62 encloses a resilient magnetic responsive contact reed 63having a lead 64 connected thereto and extending through one end wall ofthe capsule 62. Spaced contacts 65 and 66 within the capsule 62 areselectively engaged by the reed 63, dependent upon the actuation of thereed 63. The contacts 65 and 66 have leads 67 and 68 extending throughthe other end wall of the capsule 62.

In order to avoid the effect of the alternating field of the laminations18, and to prevent undesired actuation of the reed 63, a magneticmetallic shield 69 is provided, arcuate in shape and extending throughan arc of about 120, and of a length at least as great as that of thereed 63. The shield 69 has side legs 70 through which screws 71 extendinto threaded engagement in the block 60 so that the shield 69 can bemoved to the desired position as determined by the shielding of the reed63 desired and required.

In FIG. 9 a modified form of magnetic shield 69 is shown which can be ofnon-magnetic material such as aluminum, with a magnetic foil strip 80secured to the interior surface 81 of the shield 69. This constructionminimizes the magnetic drag by the shield on the magnet 52.

In the demand meter circuit shown in FIG. 7, for a graphic meter ofconventional type, the lead 64 is connected to one end of the secondarywinding of a transformer T 1, which serves as a source of energy. Theother end of the secondary winding of the transformer T1 is connected bya conductor 74, respectively, to the ends of advance coil 75 and releasecoil 76 for stylus operation. The other ends of the coils 75 and 76 arerespectively connected to the leads 68 and 67. Movement of the reed 63will thus energize the desired coil 75 or 76.

In the demand meter circuit shown in FIG. 8, for magnetic tape recordingwith conventional equipment, the lead 64 is connected to the capacitor78 of the tape recorder, for charging the same, through a resistor 78'to one end of the secondary winding of a supply transformer T2, theother end of the secondary winding being connected through the lead 68to the contact 66 and thus to the reed 63. The other contact 65 isconnected by the lead 67 through the demand head 79 and suppressor P sothat upon shifting of the reed 63 an impulse is sent through the demandhead 79 to magnetize the tape.

The mode of operation will now be pointed out.

The meter is actuated in the well known manner by current passingtherethrough to the place of use, eddy currents effective on the disccausing rotation thereof and of the shaft 17. Rotation of the shaft 17,through the worm and worm wheel 26, rotates the shaft 40 to actuate thewatthour register assembly 14.

Upon rotation of the shaft 40 the cylindrical magnet 52 carried therebyis also rotated to successively present its N and S poles toward thereed 63, thereby to attract the reed 63 as each pole approaches the reed63 and the reed 63 engages the contact 65. As the pole recedes the reed63 springs back and engages the contact 66, for demand contact meteractuation such as by the circuitry of FIG. 7 or FIG. 8 or other desiredcircuit.

The frame 56 can be turned about the pivot provided by the clampingscrew 58 or moved toward or away from the magnet 52.

The shield 69 is positioned as found advisable to minimize the effect ofthe alternating field of laminations 18 of the watthour meter.

A compact contact device is thus provided with which the objects of theinvention can be effected.

I claim:

1. A demand contact device for use with a watthour meter having a backhousing plate,

a register having a frame spaced forwardly of said back housing plate,

a current use responsive member, and

a register actuating shaft between said plates and actuated by saidresponsve member for actuating said register,

said device comprising,

a permanently magnetic member mounted on said shaft and rotated thereby,

said magnetic member having a periphery and poles facing said periphery,

a mounting member mounted on said frame plate,

a reed switch carried by said mounting member and having a contact and amagnetic responsive electrical conductive reed with a free end movaibletoward and away from said contact, and

a shielding member for said reed carried by said mounting member.

2. A demand contact device as defined in claim 1 in which saidpermanently magnetic member includes ceramic material, and

said mounting member is adjustably mounted on said frame plate forselective positioning with respect to said magnetic member.

3. A demand contact device as defined in claim 1 in which said shieldmember is at least as long as said reed.

4. A demand contact device com-prising a frame,

an enclosed reed switch carried in said frame and havin a magneticresponsive reed with a free end movable toward and away from a contact,

a shielding member mounted on said frame including a portion ofnon-magnetic material carrying a strip of magnetic material of a lengthat least as great as said reed, and

a rotatably mounted permanent magnetic member having spaced poles on theperiphery of said member,

said poles being movable toward and away from said reed upon rotation ofsaid member for moving said free end of said reed.

5. A demand contact device for use with a watthour meter having aregister with an actuating shaft and comprising a permanently magneticcylindrical member mounted on said shaft for rotation with said shaftabout the central longitudinal axis of said member,

said magnetic member having circumferentially spaced peripheral poleswith magnetic flux extending radially from said magnetic member,

a mounting frame member, and

an enclosed reed switch carried, by said mounting frame member inproximity to said magnetic member,

said reed switch member having a contact and a magnectic responsiveconductor reed with a free end disposed radially with respect to saidmagnetic member and movable toward and away from said contact inresponse to approach and recession of said poles,

said mounting frame member having a shielding member carried thereby andmovable in shielding relation to said reed switch.

6. In a device for counting revolutions of a shaft by magnetic means inthe presence of a strong magnetic 5 6 a shaft Whose revolutions are tobe counted, References Cited by the Examiner a permanently magneticmember mounted on said UNITED STATES PATENTS shaft for rotationtherewith,

a mounting rame memi er, 5

an enclosed reed switch carried by said mounting s f frame) member inproximity to said magnetlc 3162738 12/1964 22 gg-gg- 6 sai c i r e eswitch having a contact and a magnetic re- 3,184,624 3 1 2 y 7 Xsponsive conductor reed with a free end movable 10 O 9 6 Wmmss X withrespect to said contact in response to move- FOREIGN PATENTS ment withrespect thereto of one of said poles, 992 852 5/1965 England and ashielding member carried by said frame and dis- 1169:559 6/1964 Germanyposed in shielding relation to said reed switch and shielding it fromthe influence of said strong mag- 15 BERNARD GILHEANY Prlma'y Examinernetic field. J. J. BAKER, R. N. ENVALL, JR., Assistant Examiners.

1. A DEMAND CONTACT DEVICE FOR USE WITH A WATTHOUR METER HAVING A BACKHOUSING PLATE, A REGISTER HAVING A FRAME SPACED FORWARDLY OF SAID BACKHOUSING PLATE, A CURRENT USE RESPONSIVE MEMBER, AND A REGISTER ACTUATINGSHAFT BETWEEN SAID PLATES AND ACTUATED BY SAID RESPONSVE MEMBER FORACTUATING SAID REGISTER, SAID DEVICE COMPRISING, A PERMANENTLY MAGNETICMEMBER MOUNTED ON SAID SHAFT AND ROTATED THEREBY, SAID MAGNETIC MEMBERHAVING A PERIPHERY AND POLES FACING SAID PERIPHERY, A MOUNTING MEMBERMOUNTED ON SAID FRAME PLATE, A REED SWITCH CARRIED BY SAID MOUNTINGMEMBER AND HAVING A CONTACT AND A MAGNETIC RESPONSIVE ELECTRICALCONDUCTIVE REED WITH A FREE END MOVABLE TOWARD AND AWAY FWOM SAIDCONTACT, AND A SHIELDING MEMBER FOR SAID REED CARRIED BY SAID MOUNTINGMEMBER.